Switching content language on Koha OPAC with user interface locale switching

How to display custom content in the user’s own language on the OPAC.

Last week Mr. Ahmad Nasser from the Future University of Egypt reached out for a bit of help. The Koha OPAC provides certain sections / blocks on the OPAC e.g. OpacNav, OpacNavBottom, OpacNavBottom and OpacMainUserBlock etc. where libraries can add custom content / instructions / links / widgets to aid and inform their users better about their library and its services. Nasser’s case was interesting since he needed to cater to a bi-lingual readership where some users may prefer to read the information presented in Arabic rather than in English.

Development of language was the greatest break through of human technology. It helps us to communicate. But the same language when it is not the same for a group of people can create problem. How do a Bengali communicate with a Tamil, a Malayali with an Assamese when they do not understand the others’ language and they do not happen to speak English the global lingua-franca? Sort of like this line from this famous song pictured on Raj Kapoor in his super hit 1955 super hit –  Shree 420 that goes “mera joota hain Japani, yeh patloon engleesthani, saar pe topi russi….” (‘My shoes are Japanese, these pants are from England, the red hat on my head is Russian…’) – indeed how do we cater to this diversity!

Still image copyright: Shemaroo Videos

When it comes to a software like say Koha, the answer lies in localization – a process which allows a software to present information to its users in their own language of choice.

Koha’s user interface (UI) locale switching allows for users to switch the user interface language e.g. from default English to say Chinese (Taiwanese) or Hindi (India) as long as the language pack exists for Koha. However, this switching is not designed to tackle switching the language of the content in these custom blocks which we mentioned in the previous paragraphs.

Nasser wanted a way to display the content of say OpacMainUserBlock in Arabic when the user switched the user interface to Arabic and back in English when another user wanted to use the default language (i.e. english). This post highlights one ways by which Koha administrators / librarians can let their users a way to see the content in the language of their choice rather than an arbitrary default language or even worse a mish-mash of two or more languages.

This case is relevant to libraries in India as well, with our multitude of languages – 22 official languages at the last count – How do we serve content in English to our top 10 – 15% population, at the same time how do we address the rest of our population who are literate in their own language, all who may be some day be using Koha. Our records may be in the local regional language, but how about the added custom content? This solution works by looking at present locale[1] selected the user on the Koha OPAC.

The Solution

As I’ve mentioned this is not the only way to solve this problem. But it is probably the simplest *and* the cleanest one. And it does so by using three things:

  • The selected locale language of the Koha OPAC
  • One line of custom CSS placed into OpacUserCSS system preference
  • Exactly 3 lines of Javascript added to OpacUserJS system preference

In this blog post, we’re only looking at managing the OpacMainUserBlock – the central block on the OPAC, but the solution can be applied to every other blocks that access custom HTML markup – including OpacHeader, OpacCredits  as well as on “Koha as CMS” pages etc.

If you have never setup multiple language support on Koha, you can read up – “Installation of additional languages for OPAC and INTRANET staff client” and familiarize yourself first.

The Demo

I’ve set up a multiple language demo Koha installation with the following languages aside from the default English:

(a) Arabic (ar-Arab)
(b) Czech (cs-CZ)
(c) German (de-DE)
(d) Hindi (hi)
(e) Slovak (sk-SK)
(f) Chinese (Taiwanese: zh-Hans-TW)

The URL is https://demo-opac.l2c2academy.co.in/cgi-bin/koha/opac-main.pl where you can see this working in action. As you change the selected language and right click to see source code of the page, you will notice that the “lang” attribute of the “html” element changes to the language codes given inside the parentheses above. Below is a snapshot of 6 of the 7 languages as rendered in the HTML source once you change the language.


Hint: That lang attribute is our locale identifier and it changes every time we select a different language. Try it out on the demo and see it for yourself.

Since this depends on using CSS to toggle the visibility of our local language content we are going to define a disabled class in our OpacUserCSS system preference like this:

/* disabled class */

.disabled {
   display: none;

In this example we will use a <div> element like given below:

<div class="en disabled">

 your local language content goes here


However we can use this technique on *any* HTML element whose visibility can be toggled by accessing its display CSS property [2]. We will need to add two extra classes to our HTML element – the first one class will be named as our lang attribute and the second class will be the disabled class. We’ll need to repeat this definition for each language that we want to deal with.

For your reference here is a listing of my OpacMainUserBlock for this example, please download and study it in order to understand the process better.

NOTE: For this example, I’ve selected a single paragraph from the entry on “Wikipedia” from the Arabic, Czech, German, English, Hindi, Slovak and Chinese Wikipedia.

Once, our custom HTML is in place, we will need a way to toggle their visibility (CSS display property) based on the user selected language locale via the lang attribute. For this we’ll use the following JQuery snippet in our OpacUserJS system preference:

$(document).ready(function() {

  var selectedlang = $('html')[0].lang;

  var buildClassString = ".".concat(selectedlang);



The first line finds out the lang attribute of our <html> element. In the next line we build a string to hold the selector for the class (since classes are notified in JQuery selectors using a dot in front of the class name). And finally, in the third line, we remove the disabled class from the content whose language class matches the lang attribute. By removing the class from the element, we automatically cause its display CSS property to become visible.

What really happens behind the scenes

The custom HTML markup is first loaded with its visibility turned off. Once the page is loaded the document.ready() JQuery call looks up the current language selected and removes the display: none; CSS style from the element by removing the disabled class. As a result, the element and the content it is designated to display becomes visible. This whole cycle is repeated when we select another language. Thus, we are now able to provide our users with custom HTML markup and content based on the language they selected.


[1] “Locale (computer software) – Wikipedia, the free encyclopedia

[2] “CSS/Properties/display – W3C Wiki

CSS Quicktips : Removing RSS feed links from the Koha OPAC

Earlier today a fellow Koha user had asked :

“How to deactivate the News RSS link in OPAC?”

news rss feed link

The RSS feed link is contained in a <div> with the id named rssnews-container. In order to handle its visibility we need to simply add the following line to our OPACUserCSS system preference:

#rssnews-container {
    display: none !important;

And while we are on the topic, there is also another location where the RSS feed link shows up and that is in our OPAC search results page.


In this case however our approach needs to be slightly different as the link is presented as an anchor (a) element with the associated class rsssearchlink. Other than using a different CSS selector, rest of it is same i.e. we need to turn off the visibility of the element like this:

a.rsssearchlink { display: none !important; }

As we commonly say in Bengaluru (erstwhile Bangalore) – Enjoy maaDi 🙂